One of the most reliable and consistent methods for measuring the velocity of a moving fluid medium involves the tagging of a fluid element and measuring of the time period required for the tagged fluid element to flow from one station to another of known distance of separation therebetween. This method of the fluid velocity measurement is commonly practiced by tagging the moving fluid with a float, neutrally buoyant marker or by dyeing the fluid with a color. In spite of this method of fluid velocity measurement practiced for centries, no one has attempted to construct a flow meter using the aforementioned principle for industrial and/or scientific applications because no one has succeeded to provide a means for marking the moving fluid without adding a foreign object thereto or contaminating thereof.
The primary object of the present invention is to provide a flow meter that employs pulsed eddy flows to mark the moving fluid element in measuring the flow velocity, which pulsed eddy flows are generated by an eddy generator in an intermittent pattern.
Another object is to provide a flow meter that employs an eddy sensor disposed at a station downstream from the location of the eddy generator, wherein the representative flow velocity is obtained by dividing the distance between the pulsed eddy generator and the eddy sensor by the time interval between the generation of a pulsed eddy stream by the pulsed eddy generator and the sensing of the same pulsed eddy stream by the eddy sensor.
A further object is to provide a flow meter including means for calibrating and/or statistically analysing the representitive fluid velocity obtained by the pulsed eddy marking of the moving fluid element in converting the representative flow velocity into the rate of flow data.
Yet another object is to provide a flow meter employing a pulsed eddy generator automatically activated to generate an eddy stream moving with the flowing fluid following a predetermined brief period of inactivation providing a silent stream, wherein the eddy generator under activated mode is deactivated by the eddy sensor at the moment the eddy sensor detects the leading edge of the eddy stream generated by the eddy sensor; whereby, the eddy generator produces a series of eddy streams separated by a series of silent streams.
Yet a further object is to provide a flow meter including means for obtaining the time rate of flow data from the representative flow velocity that is calculated by dividing the distance between the eddy generator and eddy sensor by the time period between sensing the leading edges of two consecutive pulsed eddy streams measured by the sensor minus the predetermine duration of each silent stream.
These and other objects of the present invention will become clear as the description thereof proceeds.